Arduino UNO COM port problems

So I've had an Arduino UNO for a year or so now, and everything works fine with the actual board. I lent it to an interested friend for a while and kept the same Arduino IDE on my Windows 10 PC. My friend used a Mac to mess with it, but I didn't think it would matter (I'm new to this; I never played with the Arduino much until today). He did the same basic projects on it that I did. Today I got it back, plugged it in, and the UNO turned on (no sensors attached). When I try to run the Blinking_LED program, I get this error message:

avrdude: ser_open(): can't open device "\.\COM3": The system cannot find the file specified.

Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

Also, when I try to reset the COM port, I go to Tools, but the option "Port" is unhighlighted and will not let me click it. I've deleted and re-dowloaded the IDE to my PC but I'm still encountering the exact same problems. Any suggestions on how to resolve this would be GREATLY appreciated! :) P.S. If it makes any difference, the PC has no reaction to the UNO being plugged in.

Sounds like he might have broken it.

If windows does not even know its there chances are he did something to damage it without knowing.

You should try other USB ports (not USB 3.0), Another USB cable, If its a clone then re-install the CH340 drivers. and dont forget that in win 10 the COM ports are under HIDDEN DEVICES.

Thanks a lot, apparently the USB I was using only supplied power but won't communicate with the board. Sorry for the overthinking... it's working perfectly fine now!

Hello friends i have win 10 and write 2 time program on arduino uno and now no com port show in device manager guide me

Hasibjani ==> Win 10 has the "feature" of hiding the Ports from you in Device Manager. If your complaint is that Device Manager does not show an item Ports -- then, in Device Manager, select View then select Show Hidden Devices.

"Ports (COM and LPT)" will then show in the devices list. Your UNO should appear as USB_SERIAL CH340 (if you have the same board I do).